Revert "host/i386: assume presence of POPCNT"

This reverts commit 45ccdbcb24.
The x86-64 instruction set can now be tuned down to x86-64 v1
or i386 Pentium Pro.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

host/include/i386/host/cpuinfo.h

@@ -11,6 +11,7 @@
 #define CPUINFO_ALWAYS          (1u << 0)  /* so cpuinfo is nonzero */
 #define CPUINFO_MOVBE           (1u << 2)
 #define CPUINFO_LZCNT           (1u << 3)
+#define CPUINFO_POPCNT          (1u << 4)
 #define CPUINFO_BMI1            (1u << 5)
 #define CPUINFO_BMI2            (1u << 6)
 #define CPUINFO_AVX1            (1u << 9)

tcg/i386/tcg-target.h

@@ -111,6 +111,7 @@ typedef enum {
 #endif
 
 #define have_bmi1         (cpuinfo & CPUINFO_BMI1)
+#define have_popcnt       (cpuinfo & CPUINFO_POPCNT)
 #define have_avx1         (cpuinfo & CPUINFO_AVX1)
 #define have_avx2         (cpuinfo & CPUINFO_AVX2)
 #define have_movbe        (cpuinfo & CPUINFO_MOVBE)
@@ -142,7 +143,7 @@ typedef enum {
 #define TCG_TARGET_HAS_nor_i32          0
 #define TCG_TARGET_HAS_clz_i32          1
 #define TCG_TARGET_HAS_ctz_i32          1
-#define TCG_TARGET_HAS_ctpop_i32        1
+#define TCG_TARGET_HAS_ctpop_i32        have_popcnt
 #define TCG_TARGET_HAS_deposit_i32      1
 #define TCG_TARGET_HAS_extract_i32      1
 #define TCG_TARGET_HAS_sextract_i32     1
@@ -177,7 +178,7 @@ typedef enum {
 #define TCG_TARGET_HAS_nor_i64          0
 #define TCG_TARGET_HAS_clz_i64          1
 #define TCG_TARGET_HAS_ctz_i64          1
-#define TCG_TARGET_HAS_ctpop_i64        1
+#define TCG_TARGET_HAS_ctpop_i64        have_popcnt
 #define TCG_TARGET_HAS_deposit_i64      1
 #define TCG_TARGET_HAS_extract_i64      1
 #define TCG_TARGET_HAS_sextract_i64     0

util/cpuinfo-i386.c

@@ -35,6 +35,7 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
         __cpuid(1, a, b, c, d);
 
         info |= (c & bit_MOVBE ? CPUINFO_MOVBE : 0);
+        info |= (c & bit_POPCNT ? CPUINFO_POPCNT : 0);
         info |= (c & bit_PCLMUL ? CPUINFO_PCLMUL : 0);
 
         /* NOTE: our AES support requires SSSE3 (PSHUFB) as well. */